MIC3775 750mA µCap Low-Voltage Low-Dropout Regulator General Description Features The MIC3775 is a 750mA low-dropout linear voltage regulators that provides low-voltage, high-current output from an extremely small package. Utilizing Micrel’s proprietary Superβeta PNP® pass element, the MIC3775 offers extremely low-dropout (typically 280mV at 750mA) and low ground current (typically 7.5mA at 750mA). The MIC3775 is ideal for PC add-in cards that need to convert from standard 5V to 3.3V or 3.0V, 3.3V to 2.5V or 2.5V to 1.8Vor 1.65V. A guaranteed maximum dropout voltage of 500mV over all operating conditions allows the MIC3775 to provide 2.5V from a supply as low as 3.0V and 1.8V or 1.5V from a supply as low as 2.25V. The MIC3775 is fully protected with overcurrent limiting, thermal shutdown, and reversed-leakage protection. Fixed and adjustable output voltage options are available with an operating temperature range of –40°C to +125°C. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • Fixed and adjustable output voltages to 1.24V • 280mV typical dropout at 750mA – Ideal for 3.0V to 2.5V conversion – Ideal for 2.5V to 1.8V or 1.65V conversion • Stable with ceramic capacitor • 750mA minimum guaranteed output current • 1% initial accuracy • Low ground current • Current limiting and thermal shutdown • Reversed-leakage protection • Fast transient response • Low-profile power MSOP-8 package Applications • • • • • • • • Fiber optic modules LDO linear regulator for PC add-in cards PowerPC™ power supplies High-efficiency linear power supplies SMPS post regulator Multimedia and PC processor supplies Battery chargers Low-voltage microcontrollers and digital logic ___________________________________________________________________________________________________________ Typical Application 1.25V/750mA Adjustable Regulator PowerPC is a trademark of IBM Corp. Super βeta PNP is a registered trademark of Micrel, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com December 2006 1 M9999-121906 Micrel, Inc. MIC3775 Ordering Information Part Number Voltage Junction Temp. Range Package MIC3775-1.5YMM 1.5V –40° to +125°C 8-Pin MSOP MIC3775-1.65BMM MIC3775-1.65YMM 1.65V –40° to +125°C 8-Pin MSOP MIC3775-1.8BMM MIC3775-1.8YMM 1.8V –40° to +125°C 8-Pin MSOP MIC3775-2.5BMM MIC3775-2.5YMM 2.5V –40° to +125°C 8-Pin MSOP MIC3775-3.0BMM MIC3775-3.0YMM 3.0V –40° to +125°C 8-Pin MSOP MIC3775-3.3BMM MIC3775-3.3YMM 3.3V –40° to +125°C 8-Pin MSOP MIC3775BMM MIC3775YMM Adj. –40° to +125°C 8-Pin MSOP Standard Pb-Free MIC3775-1.5BMM Note: For other voltages. Contact Micrel Marketing for details. Pin Configuration MIC3775-x.x (Fixed) 8-Pin MSOP (MM) MIC3775 (Adjustable) 8-Pin MSOP (MM) Pin Description Pin Number Pin Name 1 EN 2 IN Pin Function Enable (Input): CMOS-compatible control input. Logic high = enable, logic low or open = shutdown. Supply (Input). FLG Flag (Output): Open-collector error flag output. Active low = output undervoltage. 3 ADJ Adjustment Input: Feedback input. Connect to resistive voltage-divider network. 4 OUT Regulator Output. 5–8 GND Ground. December 2006 2 M9999-121906 Micrel, Inc. MIC3775 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) ......................................................6.5V Enable Voltage (VEN).....................................................6.5V Lead Temperature (soldering, 5 sec.)........................ 260°C Storage Temperature (Ts) .........................–65°C to +150°C EDS Rating................................................................ Note 3 Supply Voltage (VIN)...................................... +2.25V to +6V Enable Voltage (VEN)............................................ 0V to +6V Maximum Power Dissipation (PD(MAX)) ...................... Note 4 Junction Temperature (TJ) ........................ –40°C to +125°C Package Thermal Resistance MSOP-8 (θJA) .....................................................80°C/W Electrical Characteristics(5) VIN = VOUT + 1V; VEN = 2.25V; TJ = 25°C, bold values indicate –40°C< TJ < +125°C, unless noted. Symbol Parameter Condition VOUT Output Voltage 10mA 10mA ≤ IOUT ≤ 750mA, VOUT + 1V ≤ VIN ≤ 6V Line Regulation IOUT = 10mA, VOUT + 1V ≤ VIN ≤ 6V Load Regulation VIN = VOUT + 1V, 10mA ≤ IOUT ≤ 750mA ∆VOUT/∆T Output Voltage Temp. Coefficient, Note 6 VDO Dropout Voltage, Note 7 IGND IOUT(lim) Ground Current, Note 8 Current Limit Min Typ Max Units 1 2 % % 0.06 0.5 % 0.2 1 % –1 –2 40 IOUT = 100mA, ∆VOUT = –1% 125 IOUT = 500mA, ∆VOUT = –1% 210 IOUT = 750mA, ∆VOUT = –1% 280 IOUT = 100mA, VIN = VOUT + 1V 700 ppm/°C 200 250 mV mV mV 500 mV µA IOUT = 500mA, VIN = VOUT + 1V 3.7 IOUT = 750mA, VIN = VOUT + 1V 7.5 15 mA mA VOUT = 0V, VIN = VOUT + 1V 1.6 2.5 A 0.8 V Enable Input VEN Enable Input Voltage logic low (off) 2.25 logic high (on) IEN Enable Input Current VEN = 2.25V 1 V 10 VEN = 0.8V 30 µA 2 4 µA µA Flag Output IFLG(leak) Output Leakage Current VOH = 6V 0.01 1 2 µA µA VFLG(do) Output Low Voltage VIN = 2.250V, IOL, = 250µA 250 500 mV VFLG Low Threshold % of VOUT High Threshold % of VOUT 99.2 % 93 Hysteresis % 1 % Adjustable Output Only 1.227 1.215 Reference Voltage Adjust Pin Bias Current December 2006 3 1.240 1.252 1.265 V V 40 80 120 nA nA M9999-121906 Micrel, Inc. MIC3775 Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. 4. PD(max) = (TJ(max) – TA) ÷ θJA, where θJA depends upon the printed circuit layout. See “Applications Information.” 5. Specification for packaged product only. 6. Output voltage temperature coefficient is ∆VOUT(worst case) ÷ (TJ(max) – TJ(min)) where T J(max) is +125°C and TJ(min) is –40°C. 7. VDO = VIN – VOUT when VOUT decreases to 98% of its nominal output voltage with VIN = VOUT + 1V. For output voltages below 1.75V, dropout voltage is the input-to-output voltage differential with the minimum input voltage being 2.25V. Minimum input operating voltage is 2.25V. 8. IGND is the quiescent current. IIN = IGND + IOUT. December 2006 4 M9999-121906 Micrel, Inc. MIC3775 Typical Characteristics December 2006 5 M9999-121906 Micrel, Inc. MIC3775 Typical Characteristics (cont.) December 2006 6 M9999-121906 Micrel, Inc. MIC3775 Typical Characteristics (cont.) December 2006 7 M9999-121906 Micrel, Inc. MIC3775 Functional Characteristics December 2006 8 M9999-121906 Micrel, Inc. MIC3775 Functional Diagrams MIC3775 Fixed Regulator with Flag and Enable Block Diagram MIC3775 Adjustable Regulator Block Diagram December 2006 9 M9999-121906 Micrel, Inc. MIC3775 the same minimum capacitance over the equivalent operating temperature range. Application Information The MIC3775 is a high-performance low-dropout voltage regulator suitable for moderate to high-current voltage regulator applications. Its 500mV dropout voltage at full load and overtemperature makes it especially valuable in battery-powered systems and as high-efficiency noise filters in post-regulator applications. Unlike older NPNpass transistor designs, where the minimum dropout voltage is limited by the base-to-emitter voltage drop and collector-to-emitter saturation voltage, dropout performance of the PNP output of these devices is limited only by the low VCE saturation voltage. A trade-off for the low-dropout voltage is a varying base drive requirement. Micrel’s Superβeta PNP® process reduces this drive requirement to only 2% of the load current. The MIC3775 regulator is fully protected from damage due to fault conditions. Linear current limiting is provided. Output current during overload conditions is constant. Thermal shutdown disables the device when the die temperature exceeds the maximum safe operating temperature. The output structure of these regulators allows voltages in excess of the desired output voltage to be applied without reverse current flow. Input Capacitor An input capacitor of 1µF or greater is recommended when the device is more than 4 inches away from the bulk AC supply capacitance or when the supply is a battery. Small, surface mount, ceramic chip capacitors can be used for bypassing. Larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity of the output voltage. Error Flag The MIC3775 features an error flag (FLG), which monitors the output voltage and signals an error condition when this voltage drops 5% below its expected value. The error flag is an open-collector output that pulls low under fault conditions and may sink up to 10mA. Low output voltage signifies a number of possible problems, including an overcurrent fault (the device is in current limit) or low input voltage. The flag output is inoperative during overtemperature conditions. A pull-up resistor from FLG to either VIN or VOUT is required for proper operation. For information regarding the minimum and maximum values of pull-up resistance, refer to the graph in the “Typical Characteristics” section of the data sheet. Enable Input The MIC3775 features an active-high enable input (EN) that allows on-off control of the regulator. Current drain reduces to “zero” when the device is shutdown, with only microamperes of leakage current. The EN input has TTL/CMOS compatible thresholds for simple logic interfacing. EN may be directly tied to VIN and pulled up to the maximum supply voltage. Figure 1. Capacitor Requirements Output Capacitor The MIC3775 requires an output capacitor for stable operation. As a µCap LDO, the MIC3775 can operate with ceramic output capacitors as long as the amount of capacitance is 10µF or greater. For values of output capacitance lower than 10µF, the recommended ESR range is 200mΩ to 2Ω. The minimum value of output capacitance recommended for the MIC3775 is 4.7µF. For 10µF or greater the ESR range recommended is less than 1Ω. Ultra-low ESR ceramic capacitors are recommended for output capacitance of 10µF or greater to help improve transient response and noise reduction at high frequency. X7R/X5R dielectric-type ceramic capacitors are recommended because of their temperature performance. X7R-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. Z5U and Y5V dielectric capacitors change value by as much as 50% and 60% respectively over their operating temperature ranges. To use a ceramic chip capacitor with Y5V dielectric, the value must be much higher than an X7R ceramic capacitor to ensure December 2006 Transient Response and 3.3V to 2.5V or 2.5V to 1.8V or 1.65V Conversion The MIC3775 has excellent transient response to variations in input voltage and load current. The device has been designed to respond quickly to load current variations and input voltage variations. Large output capacitors are not required to obtain this performance. A standard 10µF output capacitor, is all that is required. Larger values help to improve performance even further. By virtue of its low-dropout voltage, this device does not saturate into dropout as readily as similar NPN-based designs. When converting from 3.3V to 2.5V or 2.5V to 1.8V or 1.65V, the NPN-based regulators are already operating in dropout, with typical dropout requirements of 1.2V or greater. To convert down to 2.5V or 1.8V without operating in dropout, NPN-based regulators require an input voltage of 3.7V at the very least. The MIC3775 regulator will provide excellent performance 10 M9999-121906 Micrel, Inc. MIC3775 with an input as low as 3.0V or 2.5V respectively. This gives the PNP-based regulators a distinct advantage over older, NPN-based linear regulators. Using the power MSOP-8 reduces the θJC dramatically and allows the user to reduce θCA. The total thermal resistance, θJA (junction-to-ambient thermal resistance) is the limiting factor in calculating the maximum power dissipation capability of the device. Typically, the power MSOP-8 has a θJA of 80°C/W, this is significantly lower than the standard MSOP-8 which is typically 160°C/W. θCA is reduced because pins 5 through 8 can now be soldered directly to a ground plane which significantly reduces the case-to-sink thermal resistance and sink-toambient thermal resistance. Low-dropout linear regulators from Micrel are rated to a maximum junction temperature of 125°C. It is important not to exceed this maximum junction temperature during operation of the device. To prevent this maximum junction temperature from being exceeded, the appropriate ground plane heatsink must be used. Minimum Load Current The MIC3775 regulator is specified between finite loads. If the output current is too small, leakage currents dominate and the output voltage rises. A 10mA minimum load current is necessary for proper regulation. Adjustable Regulator Design R1 ⎞ ⎛ VOUT = 1.240V ⎜1 + ⎟ R2 ⎠ ⎝ Figure 2. Adjustable Regulator with Resistors The MIC3775 allows programming the output voltage anywhere between 1.24V and the 6V maximum operating rating of the family. Two resistors are used. Resistors can be quite large, up to 1MΩ, because of the very high input impedance and low bias current of the sense comparator. The resistor values are calculated by: ⎞ ⎛V R1 = R2⎜⎜ OUT − 1⎟⎟ ⎠ ⎝ 1.240 Where VO is the desired output voltage. Figure 2 shows component definition. Applications with widely varying load currents may scale the resistors to draw the minimum load current required for proper operation (see above). Figure 3. Thermal Resistance Figure 4 shows copper area versus power dissipation with each trace corresponding to a different temperature rise above ambient. From these curves, the minimum area of copper necessary for the part to operate safely can be determined. The maximum allowable temperature rise must be calculated to determine operation along which curve. Power MSOP-8 Thermal Characteristics One of the secrets of the MIC3775’s performance is its power MSOP-8 package featuring half the thermal resistance of a standard MSOP-8 package. Lower thermal resistance means more output current or higher input voltage for a given package size. Lower thermal resistance is achieved by joining the four ground leads with the die attach paddle to create a single-piece electrical and thermal conductor. This concept has been used by MOSFET manufacturers for years, proving very reliable and cost effective for the user. Thermal resistance consists of two main elements, θJC (junction-to-case thermal resistance) and θCA (case-toambient thermal resistance). See Figure3. θJC is the resistance from the die to the leads of the package. θCA is the resistance from the leads to the ambient air and it includes θCS (case-to- sink thermal resistance) and θSA (sink-to-ambient thermal resistance). December 2006 Figure 4. Copper Area vs. Power-MSOP Power Dissipation (∆TJA) 11 M9999-121906 Micrel, Inc. MIC3775 PD = (VIN – VOUT) IOUT + VIN×IGND If we use a 2.5V output device and a 3.3V input at an output current of 750mA, then our power dissipation is as follows: PD = (3.3V – 2.5V) × 750mA + 3.3V × 7.5mA PD = 600mW + 25mW PD = 625mW From Figure 4, the minimum amount of copper required to operate this application at a ∆T of 75°C is 160mm2. Figure 5. Copper Area vs. Power-MSOP Power Dissipation (TA) Quick Method Determine the power dissipation requirements for the design along with the maximum ambient temperature at which the device will be operated. Refer to Figure 5, which shows safe operating curves for three different ambient temperatures: 25°C, 50°C and 85°C. From these curves, the minimum amount of copper can be determined by knowing the maximum power dissipation required. If the maximum ambient temperature is 50°C and the power dissipation is as above, 625mW, the curve in Figure 5 shows that the required area of copper is 160mm2.The θJA of this package is ideally 80°C/W, but it will vary depending upon the availability of copper ground plane to which it is attached. ∆T = TJ(max) – TA(max) TJ(max) = 125°C = maximum ambient operating TA(max) temperature For example, the maximum ambient temperature is 50°C, the ∆T is determined as follows: ∆T = 125°C – 50°C ∆T = 75°C Using Figure 4, the minimum amount of required copper can be determined based on the required power dissipation. Power dissipation in a linear regulator is calculated as follows: December 2006 12 M9999-121906 Micrel, Inc. MIC3775 Package Information 8-Pin MSOP (MM) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2002 Micrel, Incorporated. December 2006 13 M9999-121906